Centrifuge with centrifugally flushed filter



NUV- 22, 1949 G. J. sTREzYNsKl CENTRIFUGE WITH CENTRIFUGALLY FLUSHED FILTER 4 4 Shets-sheet 1 Filed March 16, 1946 /V/m/fss.-

NOV. 22, 1949 G 1 STREZYNSKl 2,488,746

CENTRIFUGE WITH CENTRIFUGALLY FLUSHED FILTER Filed March, 16, 1946 4 Sheets-Sheet 2 Wm/Ww? Nov. 22, 1949 G. J. sTREzYNsKl 2,488,746

CENTRIFUGE WITH CENTRIFUGALLY FLUSHED FILTER Filed March 16, 1946 4 Sheets-Sheet 5 WHA/ESS:

Nov. 22, 1949 G. J. sTREzYNsKl I CENTRIFUGE `WITH CENTRIFUGALLY FLUSHED FILTER I Filed March 1e, 194e 4 sheets-sheet 4 WMA/rw,"

X I 40/ UJ d G m F W/ rA/Fss:

Patented Nov. 22, 1949 UNITED STATES PATENT OFFICE CENTRIFUGE WITH CENTRIIFUGALLY FLUSHED FILTER Application March 16, 1946, Serial No. 654,894

7 Claims.

The object of the invention is to provide a centrifuge for the separation of solids from liquids. and more particularly to provide a centrifuge so functioning when the solids-liquids mixture comprises solids a portion of which are so light in weight or so ne that in any ordinary centrifugal separator they would escape with the liquid.

A preferred embodiment of the invention is shown in the accompanying drawings, in Which- Fig. 1 is a vertical sectional View taken through a part of the bowl. Fig. 1A is a detail view of part of the mechanism for opening the valves.

Fig. 2 is a horizontal section on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal section on the line 3-3 of Fig. l.

Fig. 4 is a detail view in vertical section of two units of the screening device.

Fig. 5 is a diagrammatic view showing means for effecting automatically certain operations hereinafter described.

To the hollow rotary spindle a is secured a collar b having a tight-fitting engagement with the outer shell c and the inner shell d of the centrifugal bowl. The inner shell d, enclosing the separating chamber, is of star-shaped contour and provides a series of radial pockets (six are shown) of progressively decreasing crosssectional area toward their outer ends, Whereat they are provided with orifices or peripheral discharge outlets e large enough to allow the expulsion of the larger separated solids. Aligning with the discharge oriilces e in the inner shell d are larger orices f in the outer shell c.

At the inner ends of its pockets, the inner shell d has an annular upward extension g, surrounded and supported by the top of the outer shell c, and, in turn, surrounding the outer rim h of the bowl top i. The top i is held down against a ange 32 on the inside of the extension g by a bowl ring lc threaded on the outside of the extension, the joint between the top and the extension being sealed by a packing ring 33.

It is intended to effect the discharge of separated solids from the outlets e, not continuously, but at intervals (as hereinafter more particularly described), and to this end I'provide a series of radially extending rods m, one for each outlet e, the outer ends of which function as valves to alternately open and close the outlets.v The operation of the valve rods m is controlled, by any desired means, to normally close the outlets but at short intervals to open them to flush out accumulated solids.

I have devised the following special means for controlling the operation of valve rods m. Each valve rod at its inner end is provided with an eccentric strap n surrounding an eccentric o, pivoted at p. The eccentric o is connected to a lever r by which it may be rotated about its pivot. A portion of the eccentric o is cut away for the reception of the rounded end t of an abutment screw 34 threaded in the strap n. Movement downward of the operating lever r effects inward movement of the valve rods m to open the corresponding discharge outlets e.

The pivots p for the eccentrics o are supported by posts 39 that extend upward past the pivots and support the cylinders Il and 20.

The following means are provided to intermittently move the lever r down. Mounted on the upper end of the hollow driving spindle a is a cap u, in the center of which is secured a post o carrying at its upper end an inverted cup w along which a cylindrical member a: may slide. This cylinder is normally held in the upper position shown in Fig. 1 by means of a spring y coni-ined between the cup w and the upper end, or head, of the cylinder. Above the cylinder and engaging its head is a plunger a, which is moved down at intervals, from the position shown in Fig. 1A, to depress the cylinder :1: and move the several operating levers r down to thereby retract the several valve rods m from their closing position. The plunger e may be operated by any desired means, such as by clockwork mechanism which, being old, is not shown or described; but it is preferably operated by a pressure liquid controlled by means shown in Fig. 5, hereinafter described. When, in the operation of the mechanism, the plunger is returned to its upper position, the spring y lifts the cylinder a: to the position shown in Fig. l, thereby permitting centrifugal force acting on the rods m to return them to their closing position, as shown in Fig. l.

'I'he cylinder a: is surrounded by a cylinder 20 (forming the inner wall of an annular space inside the cover i), which is spaced from the cylinder r by guides 2|, 22. The guide 22 engages a ange 23 on the lower end of the cylinder :c and limits the cylinders upward movement.

In the operation of the centrifuge not all the solids will be thrown outward into the apices of the pockets of shell d. The finer solids will move inward with the separated lighter liquid. In order to prevent the escape of line, light solids with the liquid I have provided a lilter l0 generally shown in Figs. 1 and 3 and partly in detail in Fig. 4. This filter Ii) is composed of a number of individual annular lter units, arranged one above the other around the cli" der II and held in alignment by ribs I2 on that cylinder. The filter, as a whole, is clamped between an annular surface (with a packing ring 36) on the under side of the bowl top z' and a flange 31 around the bottom of the cylinder il. The spaces between the ribs I2 provide passages for the escape of the filtered liquid. A rib 38 around the inside of the cylinder z' is of such an inside diameter that the annulus of liquid retained thereby will not touch the outside ci cylinder II but will keep the inside diameter of the filter pack covered.

The construction of the lter is shown in 'detail in Fig. 4. Each filter unit comprises a middle relatively coarse screen I3 and upper and lower circular filter membranes Id. The three elements I3, I4, I4 are secured together at their outer edges. The two filter membranes Iii diverge from the screen i3 toward their inner edges. The inner .edges of the elements I3, Ifl, 'I5 'are held spaced apart by means of narrow hat an nular rings I5. The solids that are not carried out into the apices of the pockets of the shell d will collect and accumulate on the filter membranes I4. The liquid will flow through the filter membranes I4 and escape between the rings I5 through the wires of the coarse screen I3.

The lower lter membrane of each unit is separated from the upper lter member of the unit seals the space between adjacent units.

The 'central element I4 of a filter unit need not be, literally, a screen Canvas or any other porous materialthat permits flow of filtered liquid below it by a paper gasket I6, which substantially toward the center would be equivalent to a screen.

A flange 4I, extending inward from the top lof the .cylinder II forms the top of a space into which clean liquid may be directed andffrom which is can flow through holes d2 to the interior of vthe lter I and thence outward through the filter membranes III to loosen and drive off solids collected thereon.

I do not hereinclaim as my invention thedeyscribed annular filter per se, but only as an clement of the described combination. In the operation of the centrifuge the liquidsollds mixture is fed through a conduit com prising the hollow driving spindle a, and passages and 3I into the separating bowl. As long as the valves m are in closed position, the liquidsolids mixture fills the separating space of the bowl from its periphery to a radial distance extending inward beyond the lter. The heavy or larger solids are thrown into the outer ends of the pockets of the shell d. The lighter liquid is displaced inward and penetrates the filter I 'Il and flows upward between the filter and the cylinder II. In its upward flow, the liquid passes through the level outlet provided by rib 38 and into, and thence out of, the hollow cover i. The nersolids that are carried inwardly with the liquid lodge on the outer faces of the filter membranes Ill. If these fine solids were allowed to accumulate on the lter, they would obstruct the free flow vof the liquid through the screening device. To prevent this, the valve rods m are withdrawn, at timed intervals, by the means hereinbefore described, to open the discharge outlets e, whereupon not only are the heavier solids flushed out the outletse but the liquid within and inside the filter is thrown out, thereby freeing the lter membranes Il! from any solids that have been built up thereon and carrying them to the outlets e. All the liquid in the bowl need not be discharged, it being necessary only to move the liquid level out beyond the filter. Immediately thereafter the valves m are again moved into position to close the outlets e and the first described operation is resumed.

It will be understood, from the foregoing description, that the centrifuge is operative to separate solids from liquid regardless of the specific gravity of the solids, since, when the valves m are opened, all solids on the outside of the filter are removed, and all solids will eventually be carried out with the volume of liquid that, during the opening of the valves, will be allowed to escape through the outlets e.

In order to more nearly insure the substantially complete removal from the lter of the fine solids that have accumulated on the membranes Ill of the filter, I have found it desirable to utilize for that purpose not only the liquid that, at the withdrawal of the Valve rods '1n from their seats, is within and inside of the filter and is then thrown out, but also to utilize additional liquid to backwash the filter. For this purpose there is provided a flush pipe or channel 5i) through which a flushing liquid may be introduced to the filter. rI his flush liquid need not be the same liquid that is being or that has been centrifuged, but may be any suitable solvent. Flush liquid should be admitted about concurrently with the opening of the valves m or slightly later.

The inflow of the solids-liquid mixture to the centrifuge may be arrested during the 'valveopening period, but this is not a necessary feature of the operation, since the rate of discharge through the orifices e exceeds the rate of infeed and allows the inner level of liquid in the bowl to moveout beyond the filter. However, it may be desirable to shut off the main feed about concurrently with the opening ofthe valves m and to turn on the feed about concurrently with the closing of the valves m. Such operation is within Vthe contemplated mode of operation and in some flushing110mm through pipe so and the described intermittent arrest of inflow to the centrifuge of the solids-liquid may be made to operate automatically.

In Fig. 5 there are shown means operable vfrom the machine spindle a through a gear train 52 for (l) intermittently operating a piston 2 (to effect opening of the valves m, as hereinbefore described; (2) intermittently admitting flushing water to the pipe 5I); and (3) successively admitting liquid to be purified to the centrifugal bowl, momentarily admitting wash water to the bowl, and shutting off supply of both liquids to the bowl.

Let it be assumed 'that in the sequence of operations the valves m have just been opened. In Fig. 5, the cam roller on pilot valve 5 has just before rode onto the high face of cam 2, moving valve 5 into position to connect the pressure fluid line 6G with the pipe 55, thereby moving down the piston a to effect the opening'of valves m as hereinbefore described. Immediately thereafter the cam roller on pilot valve 4 rides onto a higher (but not highest) face of cam I and moves control valve I into, and locks it in,

the position shown in Fig. 5 in which the pipe 53 is in lconnection with neither `the-pressure' line 6U nor theV exhaust line 5| and inwhich the valve 1 is locked in the position .shown to shut off flow to the bowl of either liquid to be purified or wash water. Immediately4 thereafter the cam roller on pilot valve 6 rides onto the high face of cam 3, thereby connecting the pressure line 66 with control valve 9 and moving it to the left to admit solvent liquid to pipe 50.

For a certain period thereafter, it will be understood that feed of any liquid to the bowl is shut off, the'valves m are open to Aallow discharge of heavy solids and solvent liquid is vadmitted through pipe 50i, which liquidpsupplemented by centrifugal force, is effecting a reverse flow of liquid through the screen Ill to wash therefrom such fine solids as have Icollected thereonand carry them toward the heavysolids outlets. Y 4The several control valves 1, 9 and plunger z remain in this position for a ypredetermined time.

The next series of operations starts lwith, the riding of the cam roller on pilot Valve 6 onto the low faceof cam 3 to thereby connect pipe 5d with the exhaust 5i, whereupon control valve 9 moves to the right, thus closing admission of liquid topipe 5D. roller on pilot valve 5 rides onto the low face of cam 2, thereby connecting pipe 55 with the exhaust line 5l and piston z is lifted by its actuating spring, whereupon valves m move to, closing position. Immediately thereafter the cam roller on pilot valve 4 rides onto the low face of cam l, thus connecting the exhaust line 5l with pipe 53, moving the control valve 1 to the right and thus admitting liquid to be clarified to the centrifugal bowl.

The separation of coarse solids from the admitted liquid, the movement of the coarse solids toward the outlets J, the inflow of separated liquid through the screening device I0 and the icollectio-n of fine solids on the screening device proceed as above described until the cam roller on the pilot valve 4 rides onto the highest and very short part of cam I, thereby connecting the pipe 53 with the pressure, whereupon the spring-actuated control valve 1 moves to theextreme left and for a very short period of time admits wash water to the bowl. Immediately thereafter the sequence of operations above described is resumed. V

From the foregoing description it will be under. stood that the interruption of liquid feed to the bowl, the actuation of piston z to open valves m and the admission of liquid to pipe 50 occur almost simultaneously and preferably in the order described, although these operations may be arranged to occur simultaneously, or nearly so in a different order; and that the shutting off of flow of liquid to pipe 50, the connection of piston z with the exhaust, and the admission of liquid to be clarified to the bowl occur almost simultaneously and preferably in the order described, although these operations may be arranged to occur simultaneously, or nearly so in a different order. The operations in the order described are, however, distinctly preferable.

In Fig. 5, an alternative arrangement from Fig. 1, of the mechanism for actuating valves m, is set forth. As in Fig. 1, a plunger 2 is adapted to move a cylinder at down into position to engage and swing down the levers r, the cylinder acting against the pressure of a coil spring y. The cylinder is guided by a surrounding stationary cylinder 10a. The spring y', which is contained Within cylinder 10a, surrounds cylinder Immediately thereafter. cam;

a cylinder 10 and, except when moved down by pressure fluid admitted to pipe 55, is held up by a spring 1| It will be understood that when necessary the centrifugal bowl may be completely emptied of the .mixture and cleaned by passing a suitable fluid .into the bowl. With the centrifugal bowl as illustrated, this may be accomplished by stopping rthebowl feed and maintaining the valves m in their open position for a time interval sufiicientV to completely empty the bowl, whereupon the control valve 1 may be moved manually to the left to admit wash water into the bowl. Emptying of the bowl may also be effected by stopping the bowl feed and the bowl rotation and allowing the mixture to drain out of the bowl through passages 3B and 3 l.

As will be apparent from the previous description of the illustrated embodiment of the invention, the outlet valves are moved at intervals into position to open the peripheral outlets by means which include the intermittently operated pilot valve 5 for applying pressure to lower the plunger e', piston x and the levers r, and the connections from these levers to the valve rods m; and the lterfiushing liquid is introduced through channel '55, in timed relation to the opening movement of the outlet valves bycontrol means including the timing mechanism l, 2 and 3 and the intermittently operated pilot valve 6 for applying pressure to move the feed valve 9 to the left so as to admit flushing liquid through channel 50.

What I claim and desire to protect by Letters Patent is:

l. A centrifuge for separating solids from liquids, comprising a centrifugal bowl having a separating chamber with peripheral discharge outlets and a liquid outlet disposed inwardly from the peripheral outlets, valves normally closing the peripheral outlets, a conduit for feeding to the separating chamber the mixture to be separated, a lter located in the chamber and extending generally parallel to the bowl axis, the filter being arranged in the path of centrifugally separated liquid iiowing inwardly to said liquid outlet, whereby the separated liquid in iiowing to its outlet passes through the lter against the action of centrifugal force, means for moving the valves at intervals into position to open the peripheral outlets, centrifugal force thereupon reversing the flow of liquid through the lter and flushing from the filter solids collected thereon, a channel leading directly to the central portion of the chamber opposite the inner face of the iilter and through which flushing liquid may be introduced, and control means for introducing the flushing liquid through the channel in timed relation to said opening movement of the valves, to cause the flushing liquid to be forced outwardly through the filter by centrifugal action and thereby aid in flushing solids from the filter.

2. A centrifuge as defined in claim 1, in which said control means include a feed valve in said channel for the flushing liquid, and a timing mechanism connected to both said outlet valve moving means and said feed valve to cause the outlet Valves and the feed valve to open periodically at about the same time.

3. A centrifuge as defined in claim 1, in which said control means include a feed valve in said channel for the flushing liquid, a timing mechanism connected to both said outlet valve moving means and said feed valve to cause the Outlet 7 valves and the feed valve to open periodically at about the same time, a valve in said mixture conduit, and a connection between said last. valve and the timing mechanism for closing said last valve approximately when the other valves are opened.

L1. A centrifuge as defined in claim 1,v in which said control means include a feed Valve in said channel for the flushing liquid, a timing mechanism connected to both said outlet valve moving means and said feed valve to cause the outlet valves and the feed Valve to open periodically at about the same time, a wash water line, and a valve operated by the timing mechanism to rst interrupt the mixture feed through said conduit approximately when the other Valves are opened and then connect the Wash water line to the conduit.

5. A centrifuge as defined in claim l, comprising also a perforated plate disposed between the lter and the outlet end of the flush liquid channel and through which the flush liquid is sprayed outwardly on the iilter.

6. A centrifuge as defined in claim 1, comprising also a perforated plate disposed between the iilter and the outlet end of the flush liquid channel and through which the flush liquid is sprayed outwardly on the lter, the liquid level of said liquid outlet being between the lter and said' plate.

7. A centrifuge as defined in claim 1, in which said liquid outlet is formed by an annular member at one end of the bowl and concentric with the bowl axis, said valve moving means including an axial plunger operatively connected to the valves and extending through said annular membei: in spaced relation thereto, the plunger being movable relative to the annular member through said end of the bowl.

GEORGE J. STREZYNSKI.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 560,627 Peck May 19, 1896 879,255 Goodman Feb. 18, 1908 1,050,622 De Raasloff et al. Jan. 14, 1913 1,215,337 Brown Feb. 13, 1917 1,355,559 Mauss Oct. 12, 1920 1,468,376 Cleveland Sept. 18, 1923 1,527,074 Peck Feb. 117, 1925 2,291,117 Strezynski Jul-y 28, 1942 FOREIGN PATENTS Number Country Date 198,387 Great Britain June 4, 1923 388,966 GreatBritain Mar. 9, 1933` 428,188 Great Britain May 8, 1935 42,3115 Denmark June 2,` 1930 612,803 Germany May 6, 1935 

